Whr Figures, From various sources Options

[djellison]

http://trs-new.jpl.nasa.gov/dspace/bitstre...5/1/07-3234.pdf

Awesome WHR graph for Opportunity in there - including the dust storm drop. Before the storm, the previous low for Opportunity had been about 350 on sol 850ish - and the storm took it to 120.whrs.

D

[jamescanvin]

Lots of juicy power related figures in the latest Midwinter Spirit update.

The dust factor, a measure of the proportion of sunlight penetrating the coating of dust on the solar arrays, has remained almost unchanged at 0.349 (meaning that 34.9 percent of the sunlight, direct and scattered, that reaches the arrays penetrates the dust layer to generate electricity).

Energy has been steady, averaging about 226 watt-hours each Martian day, or sol, and varying by only a couple of watt-hours. This is due in large part to a clear and stable atmosphere.

Tau, a measure of dust in the atmosphere, has ranged from 0.178 to 0.207 and averaged 0.193. As a result, between 81 percent and 84 percent of the sunlight reaching Mars continues down through the atmosphere to Spirit's solar array. (The remaining 16 percent to 19 percent is either scattered or absorbed by dust particles in the atmosphere. The portion of sunlight that's scattered also contributes to Spirit's solar array energy.)

A Tau this low means the skies above Spirit are remarkably clear. Not only that, Tau has decreased by an average of about 0.01 per week over the last month. (Though scattering and absorption are different and not exactly comparable, a clear mountain day on Earth has a Tau of 0.1-0.2.)

Plus as a bonus a breakdown of what is using the power:

MiniTES heater: 55Whr
Battery Heater: 29Whr
Everything else: 140Whr

[climber]

May be not the right place to ask since it has to deal with gain instead of Whr.
My question is : as the dust accumulates on solar panels, I guess it accumulates on HGA; so, does the dust lower down communication power when settled on the HGA?
Thanks

[climber]

Another question here.
Doug has explained in the past why the dust cannot be removed from the panel by wind using the TV screen analogy.
Now the situation is getting worse and I think that may be the dust is no longer accumulating on the panels but on the dust (that already touch the panel) instead.
Question is : can this later dust be blown by the wind easier than the one directly on the panels?
In this case we could hope for a kind of maximum accumulation (pending cleaning events) instead of a growing one.

[Nirgal]

Probably I missed something ... ( couldn't find the reference in one of the posts or status reports yet )

What is the current WHR situation (and trend estimates) for Opportunity ?

(... now that she is on her long way)

[ElkGroveDan]

Can the IDD reach any portion of the panels? I wonder what would happen if the rat brush were placed just above a spot on the panel and run for some period of time. I understand how thin the ambient air is, but I can't help but wonder if it might create a weak electrostatic vortex above the panel which would draw off some particles.

[Nirgal]

Can the IDD reach any portion of the panels? I wonder what would happen if the rat brush were placed just above a spot on the panel and run for some period of time. I understand how thin the ambient air is, but I can't help but wonder if it might create a weak electrostatic vortex above the panel which would draw off some particles.

Interesting Idea: could be worth a try at Earth in the sandbox under simulated Mars conditions ?

[climber]

Can the IDD reach any portion of the panels? I wonder what would happen if the rat brush were placed just above a spot on the panel and run for some period of time. I understand how thin the ambient air is, but I can't help but wonder if it might create a weak electrostatic vortex above the panel which would draw off some particles.

Better idea than mine a few months ago where I proposed to brush the accecible part of the panels

[dilo]

I think this plot of daily Whr for Spirit (green) and Oppy (red) can be useful. Recent drop to 89 Whrs is even more impressive!

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